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<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
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<body>


    <script>
        function Fn(username,pwd,callback) {
            // callback('123456')
             setTimeout(() => {
                if (username === 'admin' && pwd === '123456') {
                    callback('登录成功')
                } else {
                    callback('登录失败')
                }
             }, 0);
        }
        Fn('admin','123456',function (res) {
             console.log('函数调用了', res);
        })
    </script>
</body>
</html>